Differences of Warm & Cold Water Diving

[bleeb]

Cold water means more work gearing up & down. I've heard that the water temp. must be 92F for you not to ever chill. Anyone else hear that?

I assume this applies mainly to when you're in the water and conductive cooling, not evaporative. I've heard roughly similar values, that 'normal' skin temperature averaged over the whole body is roughly 31C/88F, but varies by individual. I imagine some people, particularly those from cold climes or endurance athletes, may be capable tolerating slightly colder conditions because of the ability to generate more body heat for long periods or from having a lower surface temperature.

 

[TSandM]

The big difference for me between warm and cold water diving is the amount of work involved. Cold water is heavy gear and thick exposure protection. Warm water is a light single tank, almost no ballast, and minimal exposure protection. I get tired diving cold water much more than diving warm.

How does this affect the type of diving I do? It doesn't really affect the type, but I'm generally happy with two dives a day in cold water, whereas I'll do four in warm.

How does it affect the equipment I use? Everything in cold water is chosen to be as negative as possible (within limits). Steel backplate, large steel tanks, heavy weight belt, negative fins with spring straps. And I obviously dive dry at home, with thick undergarments (thus all the weight). In the tropics, I use a Kydex backplate with a 17 lb wing, an Al80, and a 5 mil wetsuit (although I still use my Jet fins).

Do I make any alternation to my decompression plan? No. My deco strategy is planned for cold water, but I don't shorten anything in warm.

 

[Teamcasa]

Cold vs warm is almost the same as hard vs easy.

We dive in cooler waters for the most part in our drysuits and that equates to more weight and more gear. Right now our waters are much warmer and we have switched back to 7mm wetsuits - it's so much easier.

 

[BioLogic]

Besides the what's already been covered, I expect large changes in visibility may occur at thermoclines. That's common in the fresh water sites I dive -- and they're all cold at least at the bottom.

 

[Davidstealey3]

As for decompression and off gassing, your bodies first line of defence against cold is to restrict blood flow to extremadies. This can have a negative effect on off gassing. More conservative profiles are called for. I also make sure to keep moving my fingers, toes, and hands while hanging stops. I like to think it helps keep the blood flowing.

kudos on this response, i deleted most of it, but wanted to address the section above.

i agree with the moving of fingers, hands, and toes because the body wants to shun the blood flow away from these areas. and i suguest doing this durring the entire dive and not just while on a stop.

also if diving in cold water and NOT doing a deco dive, i suggest super slow accents to give the body a chance to off gas better. i would comment on doing this durring a deco dive, but as i am new to the whole deco area, i dont want to make a statement and be way off base. that is a question for experienced deco divers and tech instructors.

 

[gcbryan]

I guess the positive side of cold water diving is that ongassing is slower. Of course you need to offgass as well but if you do a NDL dive in cold water and really warm up on the surface interval you get the best of both worlds.

If you are in warm water for the dive and spend your surface interval with air conditioning this is the worst case scenario.

Not that this is how it usually happens but since everything else has been covered throughly in this thread I thought I'd add this.

 

[Crush]

I guess the positive side of cold water diving is that ongassing is slower.

At the beginning of a dive you are more likely to be warmer than at the end of a dive. Thus, "ongassing" should occur at a near-normal rate as you begin to dive. Near the end of your dive you will be colder, and blood-flow in the extremities will be poorer. The effect of cooler fluids (in cold limbs) holding more dissolved N2 is negligible. However, the decreased perfusion (i.e., delivery of arterial blood to [and from] a capillary bed) will result in your body off-gassing more slowly than at normal body temperatures, increasing the likelihood of the bends. The obvious things to do would be to stay warm, call the dive when you being to feel like you are getting too cool, dive a conservative profile, and take your time when surfacing. Strenuous activity just prior to or during a dive also increases the likelihood of DCS owing to the formation of microbubbles.

 

[Davidstealey3]

At the beginning of a dive you are more likely to be warmer than at the end of a dive. Thus, "ongassing" should occur at a near-normal rate as you begin to dive. Near the end of your dive you will be colder, and blood-flow in the extremities will be poorer. The effect of cooler fluids (in cold limbs) holding more dissolved N2 is negligible. However, the decreased perfusion (i.e., delivery of arterial blood to [and from] a capillary bed) will result in your body off-gassing more slowly than at normal body temperatures, increasing the likelihood of the bends. The obvious things to do would be to stay warm, call the dive when you being to feel like you are getting too cool, dive a conservative profile, and take your time when surfacing. Strenuous activity just prior to or during a dive also increases the likelihood of DCS owing to the formation of microbubbles.

right on brother, you hit that nail right on the head. that other guy needs to pull his books back out and look at it again. just because the water is cold, the body is still warm and it takes time for the core temp to drop. this is some of the reasoning in ice diving. take a little more time to plan the dive and have some contingencies. conservative dives, slow asscents, and longer safety stops makes for safer cold water diving, not to mention staying hydrated.

 

[Walter]

There are some incorrect generalizations in this thread. For the most part, the olny difference is cold water is cold and warm water is warm. Cold water will require more exposure protection which will require more lead. Cold water will increase air consumption and require a more conservative approach to decompression.

The best visibility in the world is under ice caps while I routinely dive in 86° water where I measure visibility in inches.

 

[fppf]

Yep, under ice caps, where there is limited sun light, no wind and waves, little current.
Come up here and do a river drift in January with us. Your lucky to have a foot of vis. Lake Erie in the spring is just as bad.

Generally speaking warmer waters have better vis, generally.